In general, in the case of a sensor array, particularly, a capacitive fingerprint sensor array, when a fingerprint touches a protective film above a pixel electrode (sensing electrode), a difference between capacitances is generated depending on fingerprint unevenness, and a pixel circuit detects the difference to thereby recognize the fingerprint.
In the fingerprint sensor array, when the fingers touch the protective layer above the pixel electrode (sensing electrode), static electricity charged in the human body is discharged to the pixel electrode (sensing electrode), and due to the static electricity, a problem that the pixel circuit is momentarily damaged or is deteriorated in function can be generated.
To solve this, in the past, a method in which in order to protect the pixel electrode, the static electricity preventing wiring is located higher than the pixel electrode was used. However, the conventional method has a problem in that the pixel circuit of a lower part of the pixel electrode is destroyed due to the static electricity or the operation property of transistors is deteriorated.
As illustrated in FIG. 1, FIG. 2 and FIG. 3, the structure of the conventional sensor array is formed of a substrate 110, a pixel circuit 120, a pixel electrode (a sensing electrode) 130, and a protective layer 140. In general, the pixel circuit 120 is formed of transistors and has the pixel electrode (sensing electrode) 130 at its upper end to thereby transmit a signal (a difference between capacitances) to the pixel circuit 120. In such a structure, signal wirings or the pixel circuit 120 which exists in a lower part of the pixel electrode 130 has a small effect that it can be protected by a static electricity wiring 150 and high probability that it can be damaged by the static electricity.
Furthermore, in the structure of the conventional sensor array, the static electricity preventing wiring 150 should be located high enough to prevent the static electricity. For this, the static electricity preventing wiring 150 should be formed as a new construction having a different height from the pixel electrode 130. Accordingly, the structure of the conventional sensor array is disadvantageous that a manufacturing process cost increases.